the digestive system 1.why do we need food? 2.major food groups a. introduction a.carbohydrates...
TRANSCRIPT
The Digestive System
1. Why do we need food?
2. Major food groups
A. Introduction
a. Carbohydrates
b. Fats (saturated vs. nonsaturated)
c. Proteins (essential vs. nonessential)
3. Digestive system
a. Gastrointestinal tract
b. Accessory organs
The Digestive System
1. Mouth
B. Review of structure and function
a. Salivary glands
b. Chemical digestion = salivary amylase
c. Mechanical digestion = mastication
2. Basic structure of the GI tract
a. Mucosa
b. Submucosa
c. Muscularis
d. Serosa/adventitia
The Digestive System
3. Pharynx and esophagus
B. Review of structure and function
a. Deglutition reflex (swallowing)
b. Peristalsis
c. Esophageal sphincters
d. Esophageal hiatus
The Digestive System
4. Stomach
B. Review of structure and function
a. Mucous production
b. Chemical production
i. Hydrochloric acid
ii. Pepsinogen pepsin
c. Mechanical digestion = mixing waves
d. Chyme
e. Sphincters
i. Gastroesophageal
ii. Pyloric
The Digestive System
5. Small intestine
B. Review of structure and function
a. Gross anatomy
i. Pyloric sphincter
ii. Duodenum, jejunum, ileum
iii. Ileocecal sphincter
b. Microscopic anatomy
i. Villi (singular = villus)
ii. Microvilli
c. Mechanical digestion
d. Chemical digestion
The Digestive System
6. Large intestine
B. Review of structure and function
a. Gross anatomy
i. Ascending, transverse, descending, and sigmoid colon
ii. Internal and external anal sphincters
b. Mechanical digestion
c. Chemical digestion
d. Defecation reflex
The Digestive System
7. Pancreas
B. Review of structure and function
a. 99% exocrine
b. Pancreatic juice
8. Liver and gallbladder
a. Hepatic blood flow
b. Bile production
c. Bile storage
d. Other liver functions
The Digestive System
1. General changes
C. Age-related changes
a. Decreased secretions
b. Decreased motility
c. Decreased thickness of mucosa
2. Mouth
a. Loss of teeth (1/2 need dentures >65)
b. Dry mouth, usually caused by medications and/or mouth breathing
c. Decreased taste sensations
The Digestive System
3. Esophagus
C. Age-related changes
a. Dysphagias
b. Heartburn
4. Stomach
a. Chronic atrophic gastritis
b. Decreased HCl secretion = increased pH, affecting large intestinal bacteria
The Digestive System
5. Small intestine
C. Age-related changes
a. Reduced number of villi
b. Decreased enzyme production
c. Decreased capillary beds
d. No real change in absorption, however, except for vitamins B6 and B12
The Digestive System
6. Large intestine
C. Age-related changes
a. Muscle weakness may lead to diverticulosis
b. Bacterial changes (?)7. Pancreas
a. Decreased enzyme production
b. Increased incidence of blocked pancreatic ducts; therefore, increased pancreatitis
The Digestive System
8. Liver
C. Age-related changes
a. Moderate fibrosis but little functional change
b. Increased number of atypical cells
c. Decreased mitochondria per cell
d. Decreased ability to metabolize drugs
9. Gallbladder
The Digestive System
D. Age-related dysfunctions
1. Hiatal hernia
2. Cancer
a. All incidences increased with age
b. High rates of death due to advanced stage at diagnosis
3. Diverticulitis
4. Constipation
5. Fecal incontinence
6. Hemorrhoids
7. Intestinal obstruction
The Digestive System
E. Nutrition in the elderly
1. Needs do not change significantly, so good dietary habits need not change
2. Basic diet should include:
a. 55 – 60% carbohydrates (increased proportion of complex carbs)
b. 12 – 15% proteins
c. 20 – 30% fats
end
The Digestive System
F. Take home messages
1. All regions have structural changes
2. All organs have diminished secretions
3. Atrophy of muscularis leads to decreased digestive movements
4. All elderly are worried about some aspect of their digestive system
5. Nutritional changes should be related to reduced caloric intake matched with reduced activity